What code are you using to test it? If you set the servo pulse to 1.5ms, the servo should stop. If you want to travel full speed in either direction, use .75ms or 2.25ms, which is the extreme position in either direction on a normal servo. If you specify a pulse that is close to 1.5ms, the servo will rotate slowly, because it thinks it's near the destination.

I use PIC16F877A and a demo version of mikroC form mikroelektronika.This code will make a servo connected to RC2/CCP1 pin to rotate to one extreme -> wait for 1 second -> rotate to another extreme -> wait for 1 second and repeats this action.